Vitamin A-intoduction, functions, sources, storage, WHO statistics, deficiency, treatment, prevention and control of deficiencies, Vit. A deficiency in India, assessment of Vit. A deficiency, recommended allowances, toxicity.
2. VITAMINS
• Vitamins are a class of organic compounds
categorized as essential nutrients.
• They are micronutrients.
• They DO NOT yield energy, but enable the body
to use other nutrients.
• The body generally CANNOT SYNTHESIZE
THEM, so they must be provided by food.
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4. VITAMIN A
• Vitamin A consists of Retinol (pre-formed vitamin),
Retinal, Retinoic acid and ẞ-carotene (pro-vitamin)
• Some of the ẞ-carotene is converted to retinol in the
intestinal mucosa.
• I IU of Vit. A = 0.3 mcg of retinol
(or 0.55 mcg of retinol palmitate)
1 mcg of retinol = 1 RE
1 mcg of ẞ-carotene = 0.167 mcg of RE
1 mcg of other carotenoids = 0.084 mcg of RE
1 RE = 3.333 IU of Vit. A4
5. FUNCTIONS
For NORMAL VISION in dim light.
Maintaining the INTEGRITYAND NORMAL
FUNCTIONING of glandular and epithelial
tissues which lines intestinal, respiratory and
urinary tracts as well as skin and eyes.
Supports GROWTH (skeletal growth)
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6. Retinol and retinoic acid function as STEROID
HORMONES. They regulate the protein synthesis
thus involved in cell growth and differentiation.
SYNTHESIS of certain glycoproteins.
Essential for the MAINTENANCE of
proper immune system
CAROTENOIDS function as antioxidants and
reduce the risk of cancers. MAY protect against some
epithelial cancers.
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7. SOURCES
ANIMAL FOODS: Liver, eggs, butter, cheese,
whole milk, fish and meat
Fish liver oil- richest natural source of retinol
PLANT FOODS: green leafy
vegetables , most green and
yellow fruits and vegetables
, roots(carrot)
FORTIFIED FOODS: food fortified with Vit. A
such as vanaspati, margarine, milk.
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9. STORAGE
• Liver has an enormous capacity for storing
Vit.A in the form of retinol palmitate
• Under normal conditions, a well fed person has
sufficient Vit.A reserves to meet his needs for 6-
9months or more
• Free retinol is HIGHLY ACTIVE BUT TOXIC,
so it is transported in the blood stream by
combining with retinol binding protein
(produced in the liver)
• So, in severe protein deficiency, sed production
of retinol binding protein prevents mobilization
of liver retinol reserves.
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10. Deficiency-WHO statistics
• An estimated 250 million preschool children
are vitamin A deficient and it is likely that in
vitamin A deficient areas a substantial
proportion of pregnant women is vitamin A
deficient.
• An estimated 250 000 to 500 000 vitamin A-
deficient children become BLIND EVERY
YEAR, half of them DYING within 12 months
of losing their sight.
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12. A) NIGHT BLINDNESS
• Lack of Vit. A FIRST causes Night blindness.
• It is the inability to see in DIM LIGHT.
• It occurs due to impairment in dark adaptation.
• The condition may get worse if Vit. A is not
taken, especially if they suffer from diarrhoea
and other infections.
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14. B) CONJUNCTIVAL XEROSIS
• It is the FIRST SIGN of Vit.A deficiency.
• The conjuctiva becomes dry and non-wettable
• It appears muddy and wrinkled (instead of
smooth and shiny)
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16. C) BITOT’S SPOTS
• They are triangular, pearly white or yellowish,
foamy spots on the BULBAR CONJUCTIVA on
either side of the CORNEA.
• Usually bilateral
• In YOUNG children, it indicates Vit.A deficiency
• In OLDER individuals, it is often an inactive
sequelae of earlier disease.
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18. D) CORNEAL XEROSIS
• The cornea appears dull, dry and non-wettable
and eventually opaque. This stage is VERY
SERIOUS.
• In more SEVERE DEFICIENCY, there maybe
corneal ulceration
• The ulcer may heal leaving a corneal scar which
may affect vision.
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20. E) KERATOMALACIA
• It is the liquefaction of the cornea. This is an
MEDICAL EMERGENCY.
• The cornea(a part or the whole) may become soft
and may burst open.
• This process is rapid and if the eye collapses,
vision is lost.
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21. XEROPTHALMIA (dry eye)
• It refers to ALL the ocular manifestations of
Vit.A deficiency.
• It is a serious nutritional disorder leading to
blindness particularly in South-East Asia.
• It is MOST COMMON in children aged 1-3yrs,
and often related to weaning
• It is associated with PEM
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22. • Associated risk factors include ignorance, faulty
feeding practises and infections (diarrhoea and
measles)
• Andra Pradesh, Tamil Nadu, Karnataka, Bihar
and West Bengal are BADLY AFFECTED.
• The rest of the North Indian states have
LESSER cases of xeropthalmia.
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23. EXTRA-OCULAR MANIFESTATIONS
• Consists of follicular hyperkeratosis, anorexia
and growth retardation.
• Even a MILD Vit.A deficiency causes an increase
in morbidity and mortality due to
RESPIRATORY &
INTESTINAL INFECTIONS?
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24. TREATMENT
• Vit. A deficiency should be treated urgently
• Nearly ALL the early stages of Xeropthalmia can
be REVERSED by:
Administration of MASSIVE DOSE of
200,000 IU (or 110mg) of retinol palmitate
ORALLY on 2 successive days.
• ALL children with corneal ulcers are given
Vit. A whether or not a deficiency is suspected,
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25. Timing Vitamin A dosage
Immediately on diagnosis
<6months of age 50,000 IU
6-12 months of age 1 lakh IU
>12months of age 2 lakh IU
Next day Same age specific dose
At least 2 weeks later Same age specific dose
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26. PREVENTION & CONTROL
• Administration of large
doses of Vit.A
SHORT TERM
• Fortification of food
MEDIUM
TERM
• Reduction or elimination of
factors contributing to
ocular disease
LONG TERM
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27. SHORT TERM ACTIONS
• A simple technology was developed by the
National Institute of Nutrition (Hyderabad) .
• The strategy is to administer SINGLE MASSIVE DOSE
of Vit. A in oil(retinol palmitate) ORALLY.
Age group Dose Duration
Children <12months 1,00,000 IU Once every 4-
6months
Children >12months 2,00,000 IU Once every 4-
6months
Child bearing age 3,00,000IU Within 1month
of delivery27
28. MEDIUM TERM ACTIONS
• FORTIFICATION of certain food [such as
dalda(vanaspati), margarine & dried skimmed
milk] with Vit. A
• Fortification is successful only if the chosen food
is consumed in sufficient quantities by groups at
risk
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29. LONG TERM ACTIONS
REDUCING or ELIMINATING the frequency and severity
of contributory factors to ocular disease (PEM,
respiratory tract infections, diarrhoea, measles)-
i. To consume green leafy vegetables or other Vit.A rich
food
ii. Promotion of breast feeding
iii. Improvements in environmental health (such as
ensuring safe and adequate WATER SUPPLY,
maintenance of SANITARY LATRINES to safeguard
against diarrhoea)
iv. Immunization against infectious diseases (measles),
prompt treatment of diarrhoea and other infections
v. Better feeding of infants and young children
vi. Improved health services for mothers and children
vii. Social and health education. 29
30. VIT.A DEFICIENCY IN INDIA
• It is a major controllable PUBLIC HEALTH and
NUTRITIONAL PROBLEM in India
• 5.7% of children suffer from eye signs of Vit.A
deficiency
• Even mild Vit.A deficiency probably increases
morbidity and mortality in children
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31. • In 1970, a national programme for prevention of
nutritional blindness was initiated to fight this
deficiency.
• Vit.A supplementation is an integral part of RCH
programme (now a part of NRHM). It covers children
upto 5yrs of age.
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32. • The programme focuses on:
a) PROMOTING consumption of Vit.A rich food by PREGNANT
AND LACTATING WOMEN and by CHILDREN UNDER 5 YRS
OF AGE and appropriate breast feeding
b) ADMINISTRATION of massive dose of Vit.A up to 5yrs of age.
• First dose of 1lakh IU with MEASLES VACCINATION at
9months
• Second dose of 2lakh IU after 9 months (at 16-18 months, with DPT
booster)
• Subsequent doses of 2lakh IU, every 6months upto the age of
5yrs.
c) For sick children
• All children with xeropthalmia to be treated at health facilities
• All children suffering from measles to be given 1 dose of Vit.A
(if they HAVEN’T RECEIVED in the previous 1 month)
• All cases of severe malnutrition to be given 1 additional dose
of Vit.A
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33. ASSESSMENT OF VIT. A
DEFICIENCY
• It is done by population surveys employing both
CLINICAL and BIOCHEMICAL criteria
• The surveys are done on preschool
children(6months to 6years) based on
prevalence criteria
• Presence of any one of the criteria should be
considered as EVIDENCE of a xeropthalmia
problem in the community. 33
34. CRITERIA
PREVALENCE IN
POPULATION AT
RISK (6MONTHS-
6YRS)
Nightblindness > 1%
Bitot’s spots >0.5%
Corneal xerosis/corneal
ulceration/keratomalacia
>0.01%
Corneal ulcer >0.05%
Serum retinol (< 10mcg/dl) >5%
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35. RECOMMENDED ALLOWANCES
GROUP RETINOL(mcg) ẞ CAROTENE(mcg)*
ADULTS
Man 600 4800
Woman 600 4800
Pregnancy 800 6400
Lactation 950 7600
INFANTS
0-6months 350 -
6-12months 350 2800
CHILDREN
1-6yrs 400 3200
7-9yrs 600 4800
ADOLESCENTS
10-17yrs 600 4800
*Conversion ratio of 1:8 used
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36. TOXICITY
• An EXCESS intake of RETINOL causes nausea,
vomiting, anorexia and sleep disorders followed
by skin desquamation and then enlarged liver
and papillar oedema.
• HIGH intakes of CAROTENE may colour
plasma and skin.
36
*Micronutrients-because they are required by the body in very small amounts
*Egs of other micronutrients: iron, cobalt, chromium, copper, iodine, manganese, selenium, zinc, molybdenum
In food, Vit. A is found in 2 forms- retinol and B-carotene
*Animal food available as preformed Vit. A(retinol); plant food as provitamins(carotenes)
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*Fish liver oil is generally used as nutritional supplements rather than food sources
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*Green leafy vegetables are the cheapest source of Vit. A and it is available throughout the year.
*The darker the green leaves, the higher its carotene content
*The most important carotenoid is Beta-carotene which has highest Vit. A activity
*Carotenes are converted to Vit. A in the small intestine. This action is poorly accomplished in malnourished children and those suffering from diarrhoea.
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The term Xerophthalmia comprises of all the ocular manifestations of Vit.A def.
Impaired vision in dim light and in the dark, due to impaired function of specific vision cells (namely, the rods) in the retina.
*Xerosis-dryness
*Conjunctiva-lines the eyelids and surface of the eyes
Opaque-not able to be seen through; not transparent.
They are predominantly rice eating states, and rice is devoid of carotene
*Reason for 2nd point-function
First dose-immediately upon diagnosis
Next dose-mother or other responsible person can administer the dose
Addition of nutrients in amounts significant enough to render the food a good to superior source of the added nutrients. This may include addition of nutrients not normally associated with the food or addition to levels above that present in the unprocessed food
